Production of high surface area carbon blacks

ABSTRACT

This disclosure relates to an improved furnace process for producing carbon blacks by the incomplete combustion of hydrocarbonaceous feedstock wherein the resultant blacks have higher surface areas than the carbon blacks normally prepared from the feedstocks, as a result of which the blacks are particularly suitable for use in imparting conductivity properites to plastic materials and the like. This disclosure also relates to the production of a novel class of furnace blacks having excellent conductivity properites and which are characterized by high surface areas and low pH values.

This invention relates to the production of furnace blacks having manyimportant applications, such as fillers, reinforcing agents, pigmentsand the like. More particularly, the invention relates to a furnaceprocess for producing carbon blacks having high surface areas which areespecially useful as conductive carbon blacks. In general, the processfor preparing the blacks is a furnace process wherein a hydrocarbonfeedstock is cracked and/or incompletely combusted in an enclosedconversion zone at temperatures above 1800° F. to produce carbon black.The carbon black entrained in the gases emanating from the conversionzone is then cooled and collected by any suitable means conventionallyused in the art.

Accordingly, it is a primary object of this invention to provide a noveland improved process for the production of carbon blacks having surfaceareas higher than those produced by the process of this invention in theabsence of the improvement.

A further object of this invention is to provide an improved furnaceprocess for producing highly conductive carbon blacks.

It is another object of the present invention to provide a class ofnovel carbon blacks which are highly suited to impart conductiveproperties to polymer systems.

Other and different objects, advantages and features of the presentinvention will become apparent to those skilled in the art uponconsideration of the following detailed description and claims.

In accordance with this invention, it has been found that the above andstill further objects are achieved by modifying a modular or stagedprocess for producing carbon black as, for example, disclosed andclaimed in U.S. Pat. No. Re. 28,974. Such a staged process consists ofan initially prepared primary combustion zone wherein a stream of hotgaseous combustion products is formed; a second or transition zonewherein liquid hydrocarbon feedstock in the form of solid streams orcoherent jets is injected substantially transversely into the gaseouscombustion stream; and a third zone which is the reaction zone where thecarbon black is formed prior to termination of the reaction byquenching. The modification of the staged process entails adding water,in the form of water vapor and in an amount of from about 4 to 15percent by volume based on the total gaseous volume of the fuel andoxidants utilized in preparing the primary combustion, into the primarycombustion zone such that the water vapor is well mixed with the gaseouscombustion products prior to the introduction of feedstock. In apreferred embodiment of the present invention, the water is added in anamount of from about 4.6 to about 11 percent by volume and in aparticularly preferred embodiment, in an amount of from about 9 to about11 percent by volume. The water may be introduced directly into thegaseous combustion products by any suitable means or, preferably, beintroduced with the oxidant utilized in preparing the primarycombustion. In any event, as noted hereinabove, it is essential that thewater vapor be well mixed with the combustion products before thefeedstock is introduced. It is also necessary for the production of thehigh surface area blacks that the residence time in the reactor be atleast 0.5 second, and preferably at least 1.0 second, and that theoverall percent combustion for the process ranges from about 40 to about60 percent with the preferred range being from about 46 to about 57percent.

Following the quenching of the reaction, the carbon black is collectedin any of the conventional manners well known in the industry such as,for example, by bag filters alone or by utilizing cyclones together withbag filters. The collected black is then pelletized in the conventionalmanner and processed under oxidizing conditions. At this point, thenovel furnace process will yield carbon blacks having markedly highersurface areas and capable of imparting conductivity properties. It has,however, been further discovered that subjecting the pellets of carbonblack produced by the present process to processing under varyingoxidizing conditions can also result in the production of high surfacearea blacks having controlled pH values, and in particular controlled soas to be below a value of 5. The novel class of high surface areafurnace blacks are characterized by having an iodine surface area of atleast 600 m² /g, a pH value of less than 5, and a DBP value of at least160 cc/100 g. In preferred embodiments, the novel blacks arecharacterized by having an iodine surface area ranging from about 800m.sup. 2 /g to about 1100 m² /g and higher. Also, the preferred carbonblacks have a pH ranging from about 2 to about 4 with the most preferredbeing in the range of about 3 to about 4. With respect to structurelevel, the preferred DBP values are from about 180 to about 350, andhigher, with the most preferred ranging from about 180 to about 275cc/100 g.

In practicing the present process for producing high surface areablacks, the following operation is observed. A carbon black-yieldingliquid hydrocarbon feedstock is injected substantially transversely intoa pre-formed stream of hot combustion gases flowing in a downstreamdirection at an average linear velocity of at least 500 feet per second.The feedstock is injected transversely in the form of coherent jets intothe combustion gases from the periphery of the stream to a degreesufficient to achieve penetration and thereby avoid coke formation onthe walls of the carbon forming zone of the reactor. In this instance,however, the feedstock will have been injected into a preformed streamof gaseous combustion products containing added water vapor thoroughlymixed therewith. The amount of added water, as stated earlier, iscritical to the successful operation of the present process, and thisfeature together with the other indicated operations, includingrequisite overall percent combustion ranges and definite residence timesare directly related to the production of the unusually high surfacearea furnace blacks.

In the preparation of the hot combustion gases employed in preparing theblacks of the present invention, there are reacted in a suitablecombustion chamber a liquid or gaseous fuel and a suitable oxidantstream such as air, oxygen, mixtures of air and oxygen or the like.Among the fuels suitable for use in reacting with the oxidant stream inthe combustion chamber to generate the hot combustion gases are includedany of the readily combustible gas, vapor or liquid streams such ashydrogen, carbon monoxide, methane, acetylene, alcohols, kerosene. It isgenerally preferred, however, to utilize fuels having a high content ofcarbon-containing components and, in particular, hydrocarbons. Forexample, streams rich in methane such as natural gas and modified orenriched natural gas are excellent fuels as well as other streamscontaining high amounts of hydrocarbons such as various hydrocarbongases and liquids and refinery by-products including ethane, propanebutane, and pentane fractions, fuel oils and the like. As referred toherein, the primary combustion represents the amount of oxidant used inthe first stage of the modular process relative to the amount of oxidanttheoretically required for the complete combustion of the first stagehydrocarbon to form carbon dioxide and water. In the present process,the primary combustion may range from about 85 to about 300 percentcombustion, with the preferred primary or first stage combustion rangingfrom about 85 to about 150 percent combustion. In this manner there isgenerated a stream of hot combustion gases flowing at a high linearvelocity. It has furthermore been found that a pressure differentialbetween the combustion chamber and the reaction chamber of at least 1.0p.s.i. (6.9 kPa), and preferably of about 1.5 (10.3 kPa) to 10 (69 kPa)p.s.i., is desirable. Under these conditions, there is produced a streamof gaseous combustion products possessing sufficient energy to convert acarbon black-yielding liquid hydrocarbonaceous feedstock to the desiredcarbon black products. The resultant combustion gas stream emanatingfrom the primary combustion zone attains a temperature of at least about2400° F. (1316° C.), with the most preferable temperatures being atleast above about 3000° F. (1649° C.). The hot combustion gases arepropelled in a downstream direction at a high linear velocity which isaccelerated by introducing the combustion gases into an enclosedtransition stage of smaller diameter which may, if desired, be taperedor restricted such as by means of a conventional venturi throat. It isat this point in the process, which is regarded as the second stage,where the feedstock is forcefully injected into the stream of hotcombustion gases.

More particularly, in the second stage where the combustion gases aretraveling at high velocity and there exists a gas kinetic head of atleast above 1.0 p.s.i (6.9 kPa), a suitable liquid carbon black-yieldinghydrocarbon feedstock is injected into the combustion gases, undersufficient pressure to achieved desired penetration thereby insuring ahigh rate of mixing and shearing of the hot combustion gases and theliquid hydrocarbon feedstock. As a result of this environment, theliquid hydrocarbon feedstock is rapidly decomposed and converted tocarbon black in high yields. Suitable for use herein as hydrocarbonfeedstocks which are readily volatilizable under the conditions of thereaction are unsaturated hydrocarbons such as acetylene; olefins such asethylene, propylene butylene; aromatics such as benzene, toluene andxylene; certain saturated hydrocarbons; and volatilized hydrocarbonssuch as kerosenes, naphthalenes, terpenes, ethylene tars, aromatic cyclestocks and the like. The liquid feedstock is injected substantiallytransversely from the outer or inner periphery, or both, of the streamof hot combustion gases in the form of a plurality of small coherentjets which penetrate well into the interior regions or core of thestream of combustion gases but not to a depth such that opposing jetswould impinge. In practicing this invention, the hydrocarbon feedstockmay readily be introduced as coherent streams of liquid by forcing theliquid feedstock through a plurality of orifices having a diameterranging from 0.01 (0.25 mm) to 0.15 (3.81 mm) inch, and preferablyranging from 0.02 (0.51 mm) to 0.06 (1.52 mm) inch under an injectionpressure sufficient to achieve the desired penetration.

The amount of feedstock utilized and/or the amounts of fuel and/oroxidant employed herein will be adjusted so as to result in an overallpercent combustion of from about 40 to about 60 percent and preferablyfrom about 46 to about 57 percent. The overall combustion represents thetotal amount of oxygen used in the carbon forming process relative tothe amount of oxygen required for the complete combustion of the totalamount of hydrocarbon used in the carbon forming process so as to yieldcarbon dioxide and water. The overall combustion is usually expressed asa percentage.

The third stage of the modular process involves the provision of areaction zone which will permit sufficient residence time for the carbonblack forming reaction to occur prior to termination of the reaction byquenching. In general, although the residence time in each instancedepends upon the particular conditions and the particular black desired,the residence times of the present process are at least 0.5 second, andpreferably at least 1.0 second. Accordingly, once the carbon blackforming reaction has proceeded for the desired period of time, thereaction is terminated by spraying thereon a quench liquid, such aswater, using at least one set of spray nozzles. The hot effluent gasescontaining the carbon black products suspended therein are then passeddownstream where the steps of cooling, separating and collecting thecarbon black are carried out in conventional manner. For example, theseparation of the carbon black from the gas stream is readilyaccomplished by conventional means such as a precipitator, cycloneseparator, bag filter, or combinations thereof.

As mentioned hereinbefore, the practice of the above-described processwill result in the production of furnace blacks having high surfaceareas and excellent conductivity properties when water, in the form ofvapor, is included as an essential operation of the process. Moreparticularly, it is not merely the addition of water to the process thatresults in the production of the high surface areas of the blacks, butrather, the manner of introducing the water, the amount of water and theform in which the water is introduced. All of these features arenecessary for the proper operation of the present process. In moredetail, the added water, which may be in any physical form at the timeof addition, must, however, be in the form of water vapor within thestream of gaseous combustion products prior to the introduction of theliquid feedstock. Furthermore, the added water must be introduced underconditions such that the water is well mixed with the combustion gasstream prior to the introduction of the liquid hydrocarbon feedstock.Moreover, the amount of added water in the form of vapor found to becritical for the successful operation of the process ranges from about 4to 15 percent by volume based on the total gaseous volume of the fueland oxidant utilized in preparing the primary combustion, with apreferred amount ranging from about 4.6 to about 11 percent and aparticularly preferred range being from about 9 to about 11 percent byvolume.

The following testing procedures are used in evaluating the analyticaland physical properties of the blacks produced by the present invention.

IODINE SURFACE AREA

The iodine surface area of a carbon black is determined in accordancewith the following procedure and reported in units of square meters pergram (m² /g). A carbon black sample is placed into a size 0 porcelaincrucible equipped with a loose-fitting cover to permit escape of gasesand is devolatilized or calcined at a temperature of 1700° F. (927° C.)over a period of 7 minutes. The crucible and contents are then cooled ina dessicator, following which the top layer of calcined carbon black toa depth of about one-fourth inch is removed and discarded. From thecarbon black remaining in the crucible a convenient sample is weighed,accurate to within 0.1 milligram (mg) and then transferred into a fourounce oil sample bottle. It has been found that for carbon blacksexpected to have surface areas in the range of 300 to 750 m² /g anappropriate sample size is 0.1 gram whereas for blacks having surfaceareas in excess of 750 m² /g, an appropriate sample size is 0.05 gram.To the bottle containing the carbon black sample there is added 40milliliters (ml) of 0.0473 N iodine solution. The bottle is covered andthe contents are then shaken for ten minutes at a rate of 120 to 260back and forth trips per minute. The resulting solution is immediatelycentrifuged at a rate of 1200 to 2000 revolutions per minute (rpm) untilthe solution becomes clear, this usually covering a period of 1 to 3minutes. Immediately after centrifuging, a 25 ml aliquot of the iodinesolution, to which has been added a few drops of 1% starch solution asan end point indicator, is titrated with 0.0394 N sodium thiosulfatesolution until one drop of the sodium thiosulfate solution causes theblue color to become colorless. As a blank, 40 ml of the 0.0473 N iodinesolution is shaken, centrifuged and titrated in the same manner as abovefor the black-containing solution. The iodine surface area, expressed inm² /g, is calculated in accordance with the formula:

    S.A.=10(B-T)-4.57/1.3375

Wherein B is the titration of the blank and T is the titration of thesample.

DIBUTYL PHTHALATE (DBP) ABSORPTION NUMBER

The DBP absorption number of a carbon black, in pelleted form, isdetermined in accordance with ASTM Test Method D 2414-76.

TINT STRENGTH

The tint strength of a carbon black sample is determined relative to anindustry tint reference black in accordance with ASTM D 3265-76a.

PH VALUE OF CARBON BLACK

Into a suitable Erlenmeyer flask there are placed a 5 gram sample ofpelleted carbon black and 50 ml of distilled water. The carbonblack-containing water mixture is brought to a boiling point using anelectric hot plate, and maintained at a slow boil for a period of 10minutes but not such as to cause dryness to occur. The resulting mixtureis cooled to room temperature and the pH thereof is then determinedutilizing a pH meter equipped with glass and calomel electrodes havingan accuracy of ±0.05 pH units. Prior to determining the pH of the carbonblack, the pH meter is calibrated against two buffer solutions, onehaving a pH of 4.0 and the other having a pH of 7.0.

In order to evaluate the performance characteristics of the blacks inimparting compound moisture absorption and volume resistivityproperties, the blacks are compounded with a suitable resin, such as,ethylene/ethyl acrylate copolymer in the present instance. The compoundto be tested is prepared by incorporating the desired amount of blackinto the resin, on a weight basis. For example, compounds containingcarbon black in amounts of 12% by weight, 20% by weight and 36% byweight are commonly preferred for such evaluations.

The procedure for preparing the resin/black compounds involves addingone-half of the ethylene/ethyl acrylate resin to be used into a Banburymixer, followed by the total amount of carbon black and then theremainder of the resin. The temperature of the Banbury mixer is broughtto 100° F. (37.8° C.) and the mixing is commenced. The initial mixing iscarried out for 30 seconds at 77 rpm (No. 1 speed) under a ram pressureof 40 p.s.i. (0.276 M Pa). Thereafter, the speed is increased to 115 rpm(No. 2 speed) for a period of 45 seconds. During this cycle thetemperature reaches 100° F. (37.8° C.) whereupon the ram is raised topermit the black to be brushed back into the hopper. When thetemperature reaches 250° F. (121° C.), water is circulated through themixer housing and rotors. Following the period of mixing at 115 rpm, thespeed is increased to 230 rpm (No. 3 speed) for an additional 105seconds. At the end of this period of time, the mixing is stopped andthe resin/black compound is removed from the mixer. In the case of acompound containing 12 or 20% by weight loading of the black, thetemperature of the compound is from 260° F. (127° C.) to 290° F. (143°C.). Whereas for a 36% loading of black the compound temperature is from330° F. (166° C.) to 360° F. (182° C.). The resulting compound is thenpassed twice through a cold two-roll mill and formed into sheets for thesubsequent testing.

COMPOUND MOISTURE ABSORPTION

Sheets of the various ethylene/ethyl acrylate compounds prepared in theBanbury mixer as described above were subjected to dicing andgranulating to yield suitable test samples. A two gram sample of thegranulated compound is weighed into a glass crucible of known weight anddried overnight at 190° F. (87.8° C.) to remove any moisture in thecompound. After cooling in a desiccator, the weight is obtained to thenearest one-tenth of a milligram. The compound is then placed into adesiccator maintained at conditions of room temperature and 79% relativehumidity. The compound is then weighed after 1 hour and periodicallythereafter for 3 days and further, if needed, until constant weight isachieved. The equilibrium moisture absorption is calculated as a weightpercentage of the compound.

VOLUME RESISTIVITY

This test procedure is employed for determining the volume resistivityof plastic compounds containing carbon black. The following is adescription of the preparation from the sheeted compounds prepared inthe Banbury mixer as described earlier of the compression molded plaquesto be used as test specimens. From the sheeted compound prepared on thetwo-roll mill there are cut 7×7 inch (17.8×17.8 cm) samples. Acompression mold with a cavity of 7×7 inch (17.8×17.8 cm) in size thenlined with a release layer of polyethylene terephthalate film onto whichis placed the test specimen. As a top release covering there is provideda film of polytetrafluoroethylene film. The covered compression mold isplaced in a compression press which is maintained at a temperature of320° F. (160° C.), as for example, by introducing steam at a pressure of100 p.s.i. (0.689 MPa). When the compression mold reaches a temperatureof 320° F. (160° C.), the ram force of the compression press is raisedfrom zero to a reading of 20 tons (18,144 kg) and is so maintained for aperiod of 5 minutes. The pressure on the sample is approximately 816p.s.i. (5.63 MPa). The compression mold is then removed from the hotcompression press and placed into a cold compression press, alsomaintained at 20 tons (18,144 kg) ram force, until the molds are cooledto about room temperature. The compression molded plaque of 7×7 inch(17.8×17.8 cm) size is then removed from the mold and deflashed.

To now prepare the actual specimen for the volume resistivity testprocedure, a specimen of 2×6 inch (5.1×15.2 cm) size is cut from the 7×7inch (17.8×17.8 cm) compression molded plaque. The test specimen is thencoated on each end with a silver paint (silver conductive coating inethyl alcohol) to produce an approximately one-half inch wide silverelectrode. After drying, the uncoated portion of the specimen ismeasured to determine the exact distance between the electrodes, theaverage width and the average thickness. The specimen is then placedbetween 8×6 inch (20.3×15.2 cm) glass plates arranged crosswise to eachother such that the edge of the top plate is evenly lined with the edgeof the specimen. Brass shims are then placed on the top and bottom ofeach of the coated ends of the specimen. To the brass shims there arethen attached alligator clips which lead to a Digitac Model H102120Multimeter instrument for resistance measurements.

The resistance of the specimen is first measured into an oven maintainedat 90° C. in order to obtain a resistance measurement at thistemperature. In so doing, the resistance is initially measured after 3minutes at 90° C. with subsequent readings being taken at 2 minuteintervals for the next 30 minutes. After 30 minutes, readings are takenevery 5 minutes until the specimen has been in the 90° C. oven for atotal of 60 minutes. The value for the resistance of the specimen at 90°C. is fixed on a plot as the point where the readings become constant.The resistance measurements are then used in calculating the volumeresistivity of the specimen by means of the following formula:

    Volume Resistivity, ohms-cm=R×A/L

Wherein R is the resistance of the specimen (ohms),

A is the cross-sectional area of the uncoated portion of the specimen(cm₂), and

L is the distance between the two silver electrodes coated on each endof the specimen (cm).

The invention will be more readily understood by reference to thefollowing examples which describe the detailed preparation ofrepresentative compounds. There are, of course, many other forms of thisinvention which will become obvious to one skilled in the art, once theinvention has been fully disclosed, and it will accordingly berecognized that these examples are given for the purpose of illustrationonly, and are not to be construed as limiting the scope of thisinvention in any way.

Furthermore, as noted hereinbefore, there is a wide possibility ofavailable materials from which to select a suitable liquid feedstock andfuel for combustion. However, in all of the examples herein, the sameliquid feedstock and fuel were utilized. This in no way is intended tobe limiting upon the materials that may be employed. As the liquidhydrocarbon feedstock there is used in the examples Sunray DX which is afuel having by weight a carbon content of 90.4%, a hydrogen content of7.56%, a sulfur content of 1.5%, an asphaltenes content of 4.4%, an ashcontent of 0.049%, a hydrogen to carbon ratio of 0.995, a sodium contentof 2.8 ppm, a potassium content of 0.73 ppm. a B.M.C.I. of 135, aspecific gravity in accordance with ASTM D 287 of 1.10, an API gravityof -3.1, an SSU viscosity (ASTM D 88) at 130° F. of 542.9, and an SSUviscosity at 210° F. of 63.3. The natural gas used as the fuel in all ofthe examples herein substantially comprises, by mole percent, 9.85%nitrogen, 0.18% carbon dioxide, 86.68% methane, 3.07% ethane, 0.19%propane, 0.01% isobutane, and 0.2% n-butane.

EXAMPLE 1

In this example there is employed a suitable reaction apparatus providedwith means for supplying combustion gas-producing reactants, i.e., afuel and an oxidant, either as separate streams or as precombustedgaseous reaction products to the primary combustion zone, and also meansfor supplying both the carbon black-yielding hydrocarboneous feedstock,the combustion gases to be introduced downstream to the apparatus, meansfor introducing the additional amounts of water, etcetera. The apparatusmay be constructed of any suitable material such as metal and eitherprovided with refractory insulation or surrounded by cooling means suchas a recirculating liquid which is preferably water. Additionally, thereaction apparatus is equipped with temperature and pressure recordingmeans, means for quenching the carbon black-forming reactions such asspray nozzles, means for cooling the carbon black product and means forseparating and recovering the carbon black from other undesiredby-products.

In a more detailed description of the apparatus utilized herein, thefirst stage is employed so as to obtain a substantially completelypre-formed combustion prior to feedstock injection. As a suitable burnerthere is provided an enclosed reaction vessel having a diameter of 8.75inches (0.22 m) for a length of 40.75 inches (1.035 m) which is thenreduced conically over the next 12 inches (0.305 m) to a diameter of 5.3inches (0.135 m). Connected to the first zone, or burner section, is asecond zone referred to as the transition zone having a diameter of 5.3inches (0.135 m) and a length of 9 inches. It is in this zone that theliquid feedstock is injected as coherent streams through as manyorifices as desired. The feedstock is injected under conditionssufficient to assure a proper degree of penetration into the combustiongas stream thereby avoiding problems of coke formation in the reactor.The resultant hot gas stream then enters a third zone, referred to asthe reaction zone where the carbon black is formed. This zone extends tothe point where the reaction is quenched. In the present case thereaction zone consists of a section having a diameter of 36 inches(0.914 m) and a length of 24 feet (7.32 m) followed by a section havinga diameter of 27 inches (0.69 m) and a length of 11 feet (3.35 m).

Accordingly, in carrying out the present example, a first stagecombustion of 140% is obtained by charging into the burner air preheatedto 750° F. (399° C.) at a rate of 60,100 s.c.f.h. (0.447 m³ /s) andnatural gas at a rate of 4930 s.c.f.h. (0.0367 m³ /s) under a pressureof 15 p.s.i.g. (0.103 MPa). The chamber pressure, or burner pressure, isrecorded as 2.6 inches (8.8 kPa) of mercury. This results in a stream ofhot combustion gases flowing in a downstream direction at a high linearvelocity into the transition zone where the feedstock preheated to 400°F. (204° C.) is injected substantially transversely into the combustiongas stream at a rate of 54 gallons per hour (gph) (0.062 kg/s) under apressure of 197 p.s.i.g. (1.36 MPa). The feedstock is injected throughfour unobstructed openings each of which has a size of 0.029 inch (0.74mm) and are located peripherally to the stream of combustion gases. Thegaseous stream then enters the reaction zone where, after a residence of1.3 seconds, the stream is water-quenched to a temperature of 1370° F.(743° C.). The overall percent combustion of the reaction is 46.8%. Theanalytical and physical properties of this black are reported in Table Iwherein this black is utilized as a control for Examples 2 and 3.

EXAMPLE 2

The procedure of Example 1 is followed utilizing the apparatus describedtherein with several variations which do not prevent drawing acomparison. Specifically, the combustion air, preheated to 750° F. (399°C.), is fed into the combustion chamber at a rate of 60,100 s.c.f.h.(0.477 m³ /s) and natural gas is introduced at a rate of 4930 s.c.f.h.(0.067 m³ /s) under a pressure of 16 p.s.i.g. (0.110 MPa). In thisinstance, together with the combustion air, there is fed into the burnerwater at a rate of 20 gph (or 3510 s.c.f.h.) (0.0261 m³ /s) whichcorresponds to 5.4% by volume based on the total gaseous volume of theair and gas utilized in preparing the primary combustion. As a result ofbringing the water into the combustion chamber with the air, the wateris well mixed with the stream of combustion gases prior to feedstockinjection. Under these conditions, the primary combustion is 138.3% andthe pressure in the combustion chamber is 2.8 inches (9.4 kPa) ofmercury. Into the gaseous combustion stream containing the intermixedwater vapor there is then added the coherent jets of liquid feedstock,preheated to 395° F. (202° C.), at a rate of 55 gph (0.063 kg/s) andunder a pressure of 195 p.s.i.g. (1.35 MPa). The residence time of thereactor is 1.3 seconds and the reaction gases are waterquenched to 1340°F. (727° C.). The overall percent combustion of the run is 46.5%. Theblack is recovered in the normal manner and the analytical and physicalproperties thereof are reported in Table I.

EXAMPLE 3

The procedure of Examples 1 and 2 is followed, using the same apparatus,again with several differences in operating conditions. Here, gas is fedat a rate of 4920 s.c.f.h. (0.0366 m³ /s) under a pressure of 15p.s.i.g. (0.103 MPa) while the combustion air, preheated to 740° F.(393° C.), is fed into the burner at a rate of 60,100 s.c.f.h. (0.447 m³/s) containing water previously introduced thereinto at a rate of 40 gph(7020 s.c.f.h.) which is calculated to be 10.8% by volume based on thetotal gaseous volume of the gas and air. These conditions result in thepressure of the combustion chamber being 2.9 inches (9.8 kPa) of mercuryand a primary combustion of 138.5%. Feedstock, preheated to 387° F.(197° C.), is injected through the four unobstructed openings at a rateof 55 gph (0.063 kg/s) and under a pressure of 191 p.s.i.g. (1.32 MPa).The residence time in the reactor is 1.3 seconds following which thecarbon forming reaction is water-quenched to a temperature of 1450° F.(788° C.). The overall percent combustion of the reaction is 46.6%.Recovery of the black is carried out in the conventional way. Analyticaland physical properties of this black are reported in Table I.

                  TABLE I                                                         ______________________________________                                        Carbon Black   Example 1 Example 2 Example 3                                  ______________________________________                                        Water added, Vol. %                                                                          0         5.4       10.8                                       Iodine Surface Area, m.sub.2 /g                                                              531       566       630                                        pH             7.2       8.1       8.4                                        DBP, cc/100g   188       186       198                                        Tint Strength, %                                                                             129       131       139                                        Ethylene/Ethyl Acrylate Resin containing 12% by weight                        loading of black                                                              Volume Resistivity, room                                                      temp. ohm-cm   623       537       236                                        Volume Resistivity, 90° C.                                             ohm-cm         5021      3601      892                                        Compound Moisture                                                             Absorption, %  1.01      1.28      1.45                                       ______________________________________                                    

The next two examples, numbers 4 and 5, are included herein todemonstrate that the present invention does not affect the well-knowntechnique of increasing the overall percent combustion of a carbonblack-forming reaction in order to produce blacks having higher surfaceareas. In other words, it has already been shown by Examples 1-3 that,all other conditions being essentially similar, the addition of water inaccordance with the teachings herein will result in the production ofblacks having higher surface areas. Therefore, since it is well-known toincrease the surface area of blacks by raising the overall percentcombustion, Examples 4 and 5 demonstrate that even further increases insurface area of the blacks are achieved when the technique of thepresent invention is combined with a well-known technique. This isclearly illustrated by comparing Example 3 with Examples 4 and 5 whereinthe overall percent combustion is raised from 46.6% to 49.9% and 56.5%respectively, all else being substantially similar, especially theamount of added water, namely, 10.8% by volume and the primarycombustion of about 138%.

EXAMPLE 4

The procedure and apparatus of Examples 1-3 are utilized except as shownhereinafter. Combustion air, preheated to 760° F. (404° C.), isintroduced into the combustion chamber at a rate of 60,100 s.c.f.h.(0.447 m³ /s) and gas is introduced at a rate of 4910 s.c.f.h. (0.0365m³ /s) under a pressure of 15 p.s.i.g. (0.103 MPa). In this case, theamount of added water brought in with the combustion air is the same asthat of Example 3, namely, 40 gph (7020 s.c.f.h.) (0.0522 m³ /s) or10.8% by volume. Under these conditions, the pressure in the combustionzone or chamber is recorded as 2.6 inches (8.8 kPa) of mercury and theprimary combustion is determined to be 138.8%. The liquid feedstock,preheated to 390° F. (199° C.) is then injected through the fouropenings, each of 0.029 inch (0.74 mm) in in the form of solid streamsat a rate of 49 gph (0.057 kg/s) and under a pressure of 162 p.s.i.g.(1.12 MPa). The residence time is 1.3 seconds prior to quenching the hotgases with water to a temperature of 1400° F. (760° C.). The overallpercent combustion of the reaction is 49.9%. The black is recovered inthe normal fashion and the analytical and physical properties of theblack are reported in Table II.

EXAMPLE 5

The apparatus and procedure of Examples 1-4 is followed with severalvariations. Natural gas is introduced into the combustion zone at a rateof 4930 s.c.f.h. (0.0367 m³ /s) under a pressure of 16 p.s.i.g. (0.110MPa). The combustion air, preheated to 750° F. (399° C.), is fed in at arate of 60,100 s.c.f.h. (0.447 m³ /s) containing the same amount ofadded water as in Examples 3 and 4, namely, 40 gph (7020 s.c.f.h.)(0.0522 m³ /s) or 10.8% by volume. The combustion chamber pressure isrecorded as 2.5 inches (8.4 kPA) of mercury and the primary combustionis 138.4%. Into the combustion gas stream there is then injected theliquid feedstock, preheated to 340° F. (171° C.), at a rate of 40 gph(0.046 kg/s) and under a pressure of 152 p.s.i.g. (1.05 MPa). Thereaction is water-quenched to a temperature of 1400° F. (760° C.) aftera residence time of 1.2 seconds. The black is collected and recovered inthe normal fashion. The overall percent combustion of this reaction is56.5%. The analytical and physical properties of the black of thisexample are reported in Table II.

                  TABLE II                                                        ______________________________________                                        Carbon Black   Example 3 Example 4 Example 5                                  ______________________________________                                        Water added, Vol. %                                                                          10.8      10.8      10.8                                       Overall Combustion, %                                                                        46.6      49.9      56.5                                       Iodine Surface Area, m.sub.2 /g                                                              630       673       846                                        pH             8.4       8.3       8.3                                        DBP, cc/100g   198       219       240                                        Tint Strength, %                                                                             139       143       140                                        Ethylene/Ethyl Acrylate Resin containing a 12% by weight                      loading of black                                                              Volume Resistivity, Room                                                      Temp., ohm-cm  236       59        --                                         Volume Resistivity,                                                           90° C., ohm-cm                                                                        892       162       --                                         Compound Moisture                                                             Absorption, %  1.45      1.05      --                                         ______________________________________                                    

The data reported in Table II clearly show that the process of thepresent invention which results in increased surface area of the blackscan be enhanced when combined with an increased overall percentcombustion.

The remaining examples show the flexibility of the present process toprepare the novel furnace blacks which have very high surface areas andpH values below 5 and yet are extremely suitable for use as conductiveblacks.

EXAMPLE 6

In this example the apparatus is somewhat similar to that used inExamples 1-5 in that the transition zone is of the same dimensions butfor the presence of 4 unobstructed orifices having a size of 0.038 inch(0.97 mm) rather than 0.029 inch (0.74 mm). Furthermore, whileconceptually similar, the dimensions of the first stage of the apparatusused herein differ in that the enclosed reaction vessel has a diameterof 8.4 inches (0.213 m) for a a length of 26.6 inches (0.676 m) beforenecking down in a conical manner to a diameter of 5.3 inches (0.0135 m)over a distance of 5.3 inches (0.0135 m). In this instance, the thirdzone or the zone in which the carbon forming is completed has a diameterof 36 inches (0.914 m) and a length of 16 feet (4.88 m). Other thanthis, the remainder of the equipment is as shown previously herein.Accordingly, in carrying out the present example combustion air,preheated to 710° F. (377° C.), is fed into the combustion zone at arate of 70,700 s.c.f.h. (0.526% m³ /s) and the natural gas at a rate of6540 s.c.f.h. (0.0487 m³ /s) under a pressure of 26 p.s.i.g. (0.179MPa). Added water is brought into the reactor with the combustion air inan amount of 35 gph (6140 s.c.f.h.) (0.0457 m³ /s) or 7.3% by volume.Furthermore, oxygen is added at a rate of 7000 s.c.f.h. (0.0520 m³ /s)to the combustion chamber. Such conditions result in a primarycombustion of 180% and a combustion chamber pressure of 5.1 inches (17.2kPa) of mercury. The resultant stream of hot combustion gases flow intothe transition zone where the coherent jets of liquid feedstock areinjected thereinto from the periphery through four openings, each of0.038 inch (0.97 mm) in size. The feedstock is preheated to 400° F.(204° C.) and is fed at a rate of 101 gph (0.117 kg/s) under a pressureof 216 p.s.i.g. (1.49 MPa). The residence time of the reaction is 0.7second and the gas stream is quenched with water to a temperature of1400° F. (760° C.). The overall percent combustion of the process is48.1%. The black is collected normally and then pelletized and driedunder oxidizing conditions of a sufficient nature as to yield a blackhaving an iodine surface area of 740 m₂ /g, a pH of 3.2, a DBP of 197cc/100 g, and a tint strength of 132%. Further information appears inTable III.

EXAMPLE 7

The procedure and apparatus used herein are similar to that of Example 6with certain exceptions. Combustion air, preheated to 710° F. (377° C.),is introduced into the combustion chamber at a rate of 71,100 s.c.f.h.(0.529 m³ /s) containing mixed therewith water introduced at a rate of35 gph (6140 s.c.f.h.) (0.0457 m³ /s) which is 7.9% by volume based onthe total volume of reactants utilized to prepare the primarycombustion. The natural gas is fed into the first zone at a rate of 3340s.c.f.h. (0.0248 m³ /s) under a pressure of 10 p.s.i.g. (0.069 MPa). Inthis instance oxygen is also added into the combustion zone at a rate of3500 s.c.f.h. (0.0260 m³ /s). Under these conditions, there is obtaineda primary combustion of 298.7% and the pressure of the combustionchamber is found to be 3.2 inches (10.8 kPa) of mercury. The liquidfeedstock, preheated to 405° F. (207° C.), is then injected into thehot, high velocity stream of combustion gases, in the form of coherentjets or streams, through four (4) unobstructed openings each of which is0.036 inch (0.91 mm) in size. The liquid feedstock is injected at a rateof 99 gph (0.115 kg/s) and under a pressure of 245 p.s.i.g. (1.69 MPa).The third stage, or reaction zone, is composed of a section having alength of 24 feet (7.31 m) and a diameter of 36 inches (0.91 m) followedby a section having a length of 9 feet (2.74 m) and a diameter of 27inches (0.686 m). Following a reactor residence time of 1 second, thereaction is water-quenched to a temperature of 1400° F. (760° C.). Theoverall combustion of the process is 47.7%. The analytical and physicalproperties of this black are given in Table III.

EXAMPLE 8

Utilizing the procedure and apparatus of Example 6 with minormodifications, the following run is carried out. Combustion air,preheated to 705° F. (374° C.), is introduced into the first zone of thereaction apparatus at a rate of 71,000 s.c.f.h. (0.528 m³ /s) containingentrained therein added water which is introduced at a rate of 35 gph(6140 s.c.f.h.) (0.0457 m³ /s) or 7.7% by volume based on the gaseousvolume of reactants employed in preparing the primary combustion. Thereare also fed into the combustion chamber natural gas at a rate of 5540s.c.f.h. (0.0412 m³ /s) under a pressure of 21 p.s.i.g. (0.145 MPa) andoxygen at a rate of 3500 s.c.f.h. (0.0260 m³ /s). This results in aprimary combustion of 179.6% and the pressure of the combustion chamberis measured as 4.1 inches (13.8 kPA) of mercury. The resultant gaseousstream enters the transition zone (9 inches (0.229 m) in length by 5.3inches (0.134 m) in diameter) and the liquid feedstock, preheated to405° F. (207° C.), is injected thereinto, as solid streams, through four(4) unobstructed orifices of 0.040 inch (1.02 mm) size, at a rate of 86gph (0.100 kg/s) under a pressure of 140 p.s.i.g. (0.97 MPa) therebyobtaining proper penetration to assure good atomization and dispersionof the feedstock. The gaseous stream enters the reaction chamber whichis formed of 2 sections, one having a length of 24 feet (7.32 m) by adiameter of 36 inches (0.91 m) and the subsequent having a length of 8feet (2.44 m) and a diameter of 27 inches (0.686 m), therein, after aresidence time of 1 second, the reaction is water-quenched to 1400° F.(760° C.). Thereafter, the black is collected and pelletized and driedunder oxidizing conditions. The overall percent combustion of theprocess is 47.9%. Analytical and physical properties of this black arereported in Table III.

EXAMPLE 9

Essentially similar apparatus and procedure as used in Example 8 isemployed herein except as follows. Combustion air, preheated to 750° F.(399° C.), is introduced into the combustion chamber at a rate of 70,700s.c.f.h. (0.526 m³ /s) containing added water injected thereinto at arate of 20 gph (3510 s.c.f.h.) (0.0261 m³ /s) which is determined to be4.5% by volume of first stage reactants. The natural gas is injectedinto the first stage at a rate of 6700 s.c.f.h. (0.05 m³ /s) under apressure of 26 p.s.i.g. (0.179 MPa). Under such conditions, the primarycombustion is 119.8% and the pressure in the combustion chamber is 3.6inches (12.2 kPa) of mercury. The hot stream of gaseous combustionproducts then enters the transition zone where liquid feedstock,preheated to 330° F. (166° C.), is injected thereinto from the peripheryunder a pressure of 320 p.s.i.g. (2.20 MPa). The feedstock is injectedthrough four (4) unobstructed openings each of which is 0.0225 inch(0.57 mm) in size at a rate of 44 gph (0.051 kg/s). Following aresidence period of 1.0 second, the reactor is water-quenched to atemperature of 1400° F. (760° C.). The overall percent combustion of theprocess is 55.5%. The black is collected and subjected to pelletizingand drying under oxidizing conditions so as to yield a low pH product.The analytical and physical properties are reported in Table III.

EXAMPLE 10

The procedure and apparatus of Example 9 are followed except as noted.Combustion air, preheated to 710° F. (377° C.), is fed into thecombustion chamber at a rate of 60,500 s.c.f.h. (0.450 m³ /s) togetherwith added water entrained therein at a rate of 31 gph (5440 s.c.f.h.)(0.0405 m³ /s), or 8.3% by volume based on the total volume of thecombustion air and natural gas used to produce the primary combustion.Natural gas is introduced into the first zone at a rate of 4910 s.c.f.h.(0.0365 m³ /s) under a pressure of 17 p.s.i.g. (0.117 MPa). The primarycombustion is determined to be 139.7% and the combustion chamberpressure is read as 2.7 inches (9.1 kPa) of mercury. The hot stream ofgaseous products then passes into the transition zone equipped with four(4) unobstructed orifices around the periphery each of 0.025 inch (0.64mm) in size. The liquid feedstock, preheated to 330° F. (166° C.) isinjected into the gaseous stream through the four orifices at a rate of41 gph (0.048 kg/s) under a pressure of 167 p.s.i.g. (1.15 MPa). Theresidence time of the reaction is 1.2 seconds prior to quenching withwater to a temperature of 1400° F. The overall percent combustion is55.9%. The black is collected, and pelletized and dried under oxidizingconditions such that a black of low pH is produced. The analytical andphysical properties of the black are given in Table III.

EXAMPLE 11

Following closely the procedure of Example 10, combustion air, preheatedto 735° F. (391° C.), is introduced into the combustion chamber at arate of 70,100 s.c.f.h. (0.522 m³ /s) containing therein added waterintroduced at a rate of 46 gph (8070 s.c.f.h.) (0.060 m³ /s) whichcorresponds to 10.5% by volume based on the total volume of air and gasused to produce the primary combustion.

                                      TABLE III                                   __________________________________________________________________________    Black Sample     Ex. 6                                                                             Ex. 7                                                                             Ex. 8                                                                             Ex. 9                                                                             Ex. 10                                                                            Ex. 11                                                                             Control.sup.+                       __________________________________________________________________________    Iodine Surface Area, m.sup.2 /g                                                                740 630 772 865 934 1029 678                                 pH               3.2 3.6 3.4 3.0 3.3 4.0  9.1                                 DBP, cc/100g     197 196 225 241 264 274  313                                 Tint Strength, % 132 121 138 134 142 148  125                                 Ethylene/ethyl Acrylate Resin Containing 12% Loading Carbon Black (by         weight)                                                                       Volume Resistivity, Room Temp.,                                               ohm-cm           --  101 49  30  22  18   13.7                                Volume Resistivity, 90° C.,                                            ohm-cm           --  131 57  29  22  17   21                                  Compound Moisture Absorption, %                                                                --  0.56                                                                              0.58                                                                              0.89                                                                              0.44                                                                              0.38 0.37                                __________________________________________________________________________     .sup.+ The control is a highly conductive carbon black obtained as a          byproduct in gasification processes utilized for the preparation of carbo     monoxide and hydrogencontaining gas mixtures involving the gasification o     hydrocarbons with oxygencontaining gases at high temperatures.           

The natural gas is introduced into the first zone at a rate of 6750s.c.f.h. (0.050 m³ /s) under a pressure of 18 p.s.i.g. (0.124 MPa). As aresult, there is produced a primary combustion of 119.9% and acombustion chamber pressure of 3.1 inches (10.4 kPa) of mercury. Theresultant hot stream of water-laden combustion gases enters thetransition zone where liquid feedstock, preheated to 310° F. (154° C.),is injected thereinto through four (4) unobstructed orifices of 0.0225inch (0.57 mm) size peripherally. The feedstock is fed at a rate of 41gph (0.048 kg/s) and under a pressure of 170 p.s.i.g. (1.17 MPa) therebyassuring proper penetration of the combustion gas stream. The residencetime in the reactor is 1.0 second followed by waterquenching of thereaction to a temperature of 1345° F. (729° C.). The overall percentcombustion of the process is 57%. The black is collected, pelletized anddried under oxidizing conditions. Further details of the black of thisexample appear in Table III.

From the above data it is apparent that the process of the presentinvention results in the preparation of furnace blacks havingexceptionally high surface areas. Moreover, the data indicate that theconductivity properties of the furnace process blacks of this inventionare reasonably comparable to that of the highly conductive gasificationprocess by-product blacks.

While this invention has been described with respect to certainembodiments, it is not so limited, and it should be understood thatvariations and modifications thereof may be made which are obvious tothose skilled in the art without departing from the spirit or scope ofthe invention.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. In a modular process forproducing furnace carbon blacks having higher than normal surface areaswherein a fuel and an oxidant are reacted in a first zone so as toprovide a stream of hot primary combustion gases possessing sufficientenergy to convert a carbon black-yielding liquid hydrocarbon feedstockto carbon black, and wherein in a second zone the liquid hydrocarbonfeedstock is peripherally injected, in the form of a plurality ofcoherent jets, into the stream of gaseous combustion products in adirection substantially transverse to the direction of flow of thestream of combustion gases and under sufficient pressure to achieve thedegree of penetration required for proper shearing and mixing of thefeedstock, and wherein in a third zone the feedstock is decomposed andconverted into carbon black prior to termination of the carbon formingreaction by quenching, and then cooling, separating and recovering theresultant carbon black, the improvement which comprises introducingwater, in the form of vapor, in an amount of from about 4 to 15% byvolume based on the total gaseous volume of the fuel and oxidantutilized in preparing the primary combustion, into the first zone suchthat the water vapor is well mixed with the stream of gaseous combutionproducts prior to the introduction of the liquid feedstock, andmaintaining the carbon black forming reaction in the third zone for aresidence time of at least 0.5 seconds, and operating the process underconditions such that the overall percent combustion thereof ranges fromabout 40 to about 60 percent.
 2. A process as defined in claim 1 whereinthe amount of water, in the form of water vapor, ranges from about 4.6to about 11% by volume.
 3. A process as defined in claim 1 wherein theamount of water, in the form of water vapor, ranges from about 9 toabout 11% by volume.
 4. A process as defined in claim 1 wherein theadded water is introduced together with the oxidant.
 5. A process asdefined in claim 1 wherein the residence time is at least 1.0 second. 6.A process as defined in claim 1 wherein the overall percent combustionranges from about 46 to about 57 percent.